123151-54-2Relevant academic research and scientific papers
Diels–Alder reaction between 1,3,3-trisubstituted-2-vinylcyclohexenes and quinones under exceptionally mild conditions: a concise entry to the cassane-type furanoditerpenoid skeleton
Tzouma, Eirini,Mavridis, Ioannis,Vidali, Veroniki P.,Pitsinos, Emmanuel N.
, p. 3643 - 3647 (2016)
Extremely mild (no metal Lewis acid catalyst, ambient temperature) and experimentally simple (no high-pressure apparatus needed) conditions were established for the Diels–Alder reaction between sterically demanding 1,3,3-trisubstituted-2-vinylcyclohexenes and non-symmetrically substituted quinones. This allowed for the successful implementation of a highly convergent strategy to the cassane-type furanoditerpenoid skeleton.
A New General Synthetic Approach to Diterpenes: Application to Syntheses of (+ -)-Taxodione and (+ -)-Royleanone.
Engler, Thomas A.,Sampath, Umashanker,Naganathan, Sriram,Velde, David Vander,Takusagawa, Fusao
, p. 5712 - 5727 (2007/10/02)
High-pressure Diels - Alder reactions of 1,3,3-trimethyl-2-vinyl-1-cyclohexenes 3a,b,i with substituted 1,4-benzoquinones afford, in good yield, highly functionalized tricyclic ring systems which are found in many classes of naturally occuring terpenes.Notably, the reactions of 3a are highly regio- and stereoselective.Efficient, formal syntheses of antitumor diterpenes (+ -)-taxodione and (+ -)-royleanone are reported, which demonstrate the practical application of this new strategy for the preparation of varied terpene systems.Of particular interest is that the high-pressure reactions are accelerated by mild Lewis acids and the regio- and stereoselectivity of these reactions is also improved under the combined high-pressure / Lewis acid conditions in comparison to the high-pressure conditions alone.Indeed, in the reaction of 3a with 2-methoxy-5-methyl-1,4-benzoquinone, ZnBr2 is required to effect the Diels-Alder reaction even at 12 kbar, and endo adduct 12c is formed stereoselectively in 90percent yield.In contrast, low-temperature Ti(IV)-catalyzed reactions of diene 3a with methoxy-substituted 1,4-benzoquinones at atmospheric pressure regioselectively produce dihydrobenzofurans 19 and 20, apparently via alkylation of the quinone Ti(IV) complex by the diene followed by the ring closure.
Regioselective preparation of tricyclic terpene ring systems by cycloaddition of 1,3,3-trimethyl-2-vinylcyclohexene with unsymmetrical quinones
Engler, Thomas A.,Naganathan, Sriram,Takusagawa, Fusao,Yohannes, Daniel
, p. 5267 - 5270 (2007/10/02)
High pressure reactions of 1,3,3-trimethyl-2-vinylcyclohexene with unsymmetrical p-benzoquinones are accelerated by ZnBr2 and regio- and stereoselectively produce substituted 4,4,10-trimethyl- and 4,4,8,10-tetramethyloctahydrophenanthrene ring systems.
